ABSTRACT

Pear is the third most widely grown fruit species in China, a region accounts for over 60% of the world’s pear cultivation area and production. Pear scab (Venturia nashicola and Venturia pirina) is one of the most serious diseases of pear. Here, we report a new interspecies hybrid (03-04-034) between Pyrus ussuriensis and Pyrus bretschneideri that exhibits consistently high resistance to Venturia nashicola. We compare its response to leaf infection by hyphae with that of its highly susceptible sister line 03-19-136, measure differences in their production of pathogenesis-related substances in response to infection, the results indicated hyphae could penetrate the cuticle of 03-04-034 in the early stages of infection and grew between cells and died finally in later infection stages, which suggested the resistance of 03-04-034 to scab was initiated by pathogen infection and occurred in later infection stages, typical of systemic acquired resistance. Experiments with the pathogen itself and with exogenous salicylic acid demonstrated 500 µg/ml salicylic acid treatment caused a resistance response similar to that induced by the pathogen, including dramatic increases in endogenous salicylic acid, polyphenols and lignification. In conclusion, 03-04-034 exhibits resistance to Venturia nashicola induced by salicylic acid at an appropriate concentration.